Heat blackberry jam, fresh blackberries, and powdered sugar over medium-low heat in a small pot, mashing blackberries into jam. Heat for a few minutes until everything is well combined. If you want it smoother, use an immersion blender or a real blender to smooth it out.
Roll out crescent roll dough into one long sheet. Spread the blackberry sauce over the crescent roll dough, leaving 1/2 to 1 inch around the entire edge empty.
Roll the crescent roll dough from the horizontal side tightly.
Cut with a knife or piece of dental floss into 12 even pieces. Put each piece into a muffin tin that's been sprayed with non-stick spray.
Bake at 375°F. for 11 to 13 minutes or until rolls are golden brown.